1. Field of the Invention
The present invention relates to an electric part, such as a throttle position sensor, used for setting the fuel supply amount in, for example, an automobile at an optimum amount in accordance with the travel speed in order to allow the automobile to travel with its fuel amount kept at the optimum amount.
2. Description of the Related Art
A description will be given of such an electric part, taking as an example the throttle position sensor disclosed in Japanese Unexamined Patent Publication No. 7-109935.
As shown in FIG. 6, a conventional electric part, such as a throttle position sensor, has a housing 11 including an accommodating portion 11a, an opening 11c formed at one end thereof in the direction of its shaft center line Z, and a cover portion 11d for sealing the opening 11c. The housing 11 also has a through hole 11e at the central portion thereof in the direction of the shaft center line Z. A metallic bearing 11g is provided at the through hole 11e, which is insert molded to the housing 11.
An operating shaft 12, made of insulating resin, has integrally formed at one end a sliding element supporting member 13 that rotates with the operating shaft 12, and is rotatably held by the bearing 11g. Sliding member pieces 13a are mounted to a surface of the sliding element supporting member 13 by staking or the like.
To the outside portion of the housing 11 at the other end of the operating shaft 12 are mounted a knob 14, a coil spring 15, an annular seal 16 and an insulating substrate 17. The knob 14 is mounted to the outside portion of the housing 11 by heat staking or the like. The coil spring 15, having one end mounted to the housing 11 and the other end mounted to the knob 14, functions to automatically return the operating shaft 12 in the direction of rotation thereof. The seal 16 is provided between the bearing 11g and the operating shaft 12. The insulating substrate 17 is disposed so as to oppose the sliding element supporting member 13.
A resistance pattern 17a is, for example, printed on a surface of the insulating substrate 17. Each of the sliding element pieces 13a slidably contact the resistance pattern 17a in order to change the resistance as the operating shaft 12 rotates, thus allowing the current or the voltage to be changed. A wave washer 18 is provided between the sliding element supporting member 13 and a protrusion 11h in the housing 11, such that the sliding element supporting member 13 is at all times urged towards the insulating substrate 17 in order to prevent the creation of play in the Z direction of the operating shaft 12.
In order to transfer the aforementioned change in resistance outside the device, one end of the internal terminal 19 is staked at an eyelet 19a or the like to the resistance pattern 17a printed on the insulating substrate 17, and the resistance pattern 17a and the internal terminal 19 are connected and fixed together. One end of the external terminal 20 inserted molded and mounted to the housing 11 is connected to the other end of the internal terminal 19 using solder 19b or the like. The resistance change is transferred to the outside of the device through the other end of the external terminal 20.
Such a conventional electrical part, or a throttle position sensors has the problem that a large number of manhours is required to assemble it, since the resistance change due to the rotation of the operating shaft 12 is transferred to the outside of the device by connecting the internal terminal 19 to the insulating substrate 17 at an eyelet 19a by staking or the like.
When staking is performed with too much strength at the eyelet 19a, the insulating substrate 17 may crack.
On the other hand, when staking is performed too weakly at the eyelet 19a, a play is created between the insulating substrate 17 and the internal terminal 19, resulting in the possibility of poor contact between the resistance pattern 17a and the internal terminal 19.
In addition, the task of assembling the electric part becomes complicated, since soldering must also be carried out using, for example, solder 19b to connect the internal terminal 19, mounted to the insulating substrate 17 at the eyelet 19a by staking or the like, and the external terminal 20 inserted molded to the housing.
In view of the above-described problems, according to a first form of the present invention, there is provided an electrical part, comprising: a hollow housing with an opening at one end and a wall surrounding the hollow; an external terminal having one end disposed in the hollow portion of the housing and the other end led out from the hollow portion of the housing; a tabular insulating substrate with a resistance pattern, which is disposed at the bottom portion of the housing; an internal terminal having a first resilient portion and a second resilient portion; and a recess-shaped terminal guide portion formed at one end of the external terminal so as to face the opening of the housing, wherein the first resilient portion of the internal terminal is inserted into and resiliently contacted with the terminal guide portion, and the second resilient portion of the internal terminal is resiliently contacted with the resistance pattern, in order to connect the external terminal and the internal terminal together.
According to a second form of the present invention, the terminal guide portion formed at one end of the external terminal may be formed by a flat portion and an opposing portion thereof of the external terminal, or a side wall of the housing and the opposing portion of the external terminal, or the flat portion of the external terminal and an opposing portion thereof of the housing.
According to a third form and a fourth form of the present invention, the electrical part may further comprise a stopper cut and raised from a flat portion of the internal terminal, wherein a recess is formed either in a flat portion of the external terminal which opposes the flat portion of the internal terminal or in a side wall of the housing, in order to retain the stopper in the recess.